Attorney general Jeff Sessions’ latest attack on the US immigration system is “an attack on core principles of who we are as a nation”, according to the head of the country’s largest body of immigration lawyers.

In Falls Church, Virginia, on Thursday, Sessions said the asylum system was rife with fraud and abuse, allowing people to enter the country illegally and threaten public safety.

“This concept that there is a nefarious intent of these individuals goes against the core of who we are as a nation,” Annaluisa Padilla, president of the American Immigration Lawyers Association (AILA), told the Guardian. “It’s very concerning.”

Sessions, who was speaking to audience of justice department lawyers, said “rampant abuse and fraud” was accomplished in the asylum process by people taking advantage of credible-fear screening, an interview conducted when people seek asylum at the border.

In the interview, an asylum officer asks questions to determine whether the applicant has a credible fear of persecution, torture or death if they are returned to their home country.

Sessions said “dirty immigration lawyers” encouraged people “to make false claims of asylum, providing them with the magic words needed to trigger the credible-fear process”. He gave examples of cases where people were found to have taken advantage of the system.

He also pointed to the increase in credible-fear interviews, which he said “went from fewer than 4,000 in 2009 to more than 73,000 by 2016 – nearly a 19-fold increase”, as proof of abuse in the system.

“There is no such thing as a magic words when it comes to the asylum process,” said Padilla. “These individuals are really the most vulnerable individuals in the immigration process.”

Sessions went on to say that because half of those who pass a credible-fear screening never file for asylum, “this suggests they knew their asylum claims lacked merit and that their claim of fear was simply a ruse to enter the country illegally”.

Padilla, whose group represents more than 15,000 attorneys and law professors who practice and teach immigration law, said that comment showed a “misunderstanding” of how the asylum system works. Instead of tens of thousands of people intentionally committing fraud, she said, it was more likely those people were confused by the complex asylum process.

After a two– or three–hour interview, which Padilla said was often traumatic, an asylum officer will tell a person who is found to have credible fear they can stay in the US.

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Sessions’ attack was personal for Padilla, whose family sought asylum in the US in 1983, fleeing Guatemala, when she was 15. She said her experience was much easier than the one facing children today.

“We have always been a nation that opens its doors not just to innovators and entrepreneurs and those who want to make this country great, but also to those who are seeking safe refuge – those who are seeking to protect their families from horrendous acts around the world,” Padilla said.

Sessions concluded his speech by encouraging Congress to adopt White House proposals for immigration reform, which were released on Sunday. On asylum, the plans specifically call for tightening standards, imposing penalties for fraud and ensuring detention while claims are processed.